An Experimental and Numerical Investigation of Crossflow Effects in Two-Phase Displacements

Abstract

SummaryIn this paper, we present flow visualization experiments and numerical simulations that demonstrate the combined effects of viscous and capillary forces and gravity segregation on crossflow that occurs in two-phase displacements in layered porous media.We report results of a series of immiscible flooding experiments in 2D, two-layered glass bead models. Favorable mobility-ratio imbibition and unfavorable mobility-ratio drainage experiments were performed. We used pre-equilibrated immiscible phases from a ternary isooctane/isopropanol/water system, which allowed control of the interfacial tension (IFT) by varying the isopropanol concentration. Experiments were performed for a wide range of capillary and gravity numbers. The experimental results illustrate the transitions from flow dominated by capillary pressure at high IFT to flow dominated by gravity and viscous forces at low IFT. The experiments also illustrate the complex interplay of capillary, gravity, and viscous forces that controls crossflow. The experimental results confirm that the transition ranges of scaling groups suggested by Zhou et al. (1994) are appropriate/valid.We report also results of simulations of the displacement experiments by two different numerical techniques: finite-difference and streamline methods. The numerical simulation results agree well with experimental observations when gravity and viscous forces were most important. For capillary-dominated flows, the simulation results are in reasonable agreement with experimental observations.